As Moore’s law deteriorates,the research and development of new materials system are crucial for transitioning into the post Moore era.Traditional semiconductor materials,such as silicon,have served as the cornerston...As Moore’s law deteriorates,the research and development of new materials system are crucial for transitioning into the post Moore era.Traditional semiconductor materials,such as silicon,have served as the cornerstone of modern technologies for over half a century.This has been due to extensive research and engineering on new techniques to continuously enrich silicon-based materials system and,subsequently,to develop better performed silicon-based devices.Meanwhile,in the emerging post Moore era,layered semiconductor materials,such as transition metal dichalcogenides(TMDs),have garnered considerable research interest due to their unique electronic and optoelectronic properties,which hold great promise for powering the new era of next generation electronics.As a result,techniques for engineering the properties of layered semiconductors have expanded the possibilities of layered semiconductor-based devices.However,there remain significant limitations in the synthesis and engineering of layered semiconductors,impeding the utilization of layered semiconductor-based devices for mass applications.As a practical alternative,heterogeneous integration between layered and traditional semiconductors provides valuable opportunities to combine the distinctive properties of layered semiconductors with well-developed traditional semiconductors materials system.Here,we provide an overview of the comparative coherence between layered and traditional semiconductors,starting with TMDs as the representation of layered semiconductors.We highlight the meaningful opportunities presented by the heterogeneous integration of layered semiconductors with traditional semiconductors,representing an optimal strategy poised to propel the emerging semiconductor research community and chip industry towards unprecedented advancements in the coming decades.展开更多
Subpixel localization techniques for estimating the positions of point-like images captured by pixelated image sensors have been widely used in diverse optical measurement fields.With unavoidable imaging noise,there i...Subpixel localization techniques for estimating the positions of point-like images captured by pixelated image sensors have been widely used in diverse optical measurement fields.With unavoidable imaging noise,there is a precision limit(PL)when estimating the target positions on image sensors,which depends on the detected photon count,noise,point spread function(PSF)radius,and PSF’s intra-pixel position.Previous studies have clearly reported the effects of the first three parameters on the PL but have neglected the intra-pixel position information.Here,we develop a localization PL analysis framework for revealing the effect of the intra-pixel position of small PSFs.To accurately estimate the PL in practical applications,we provide effective PSF(e PSF)modeling approaches and apply the Cramér–Rao lower bound.Based on the characteristics of small PSFs,we first derive simplified equations for finding the best PL and the best intra-pixel region for an arbitrary small PSF;we then verify these equations on real PSFs.Next,we use the typical Gaussian PSF to perform a further analysis and find that the final optimum of the PL is achieved at the pixel boundaries when the Gaussian radius is as small as possible,indicating that the optimum is ultimately limited by light diffraction.Finally,we apply the maximum likelihood method.Its combination with e PSF modeling allows us to successfully reach the PL in experiments,making the above theoretical analysis effective.This work provides a new perspective on combining image sensor position control with PSF engineering to make full use of information theory,thereby paving the way for thoroughly understanding and achieving the final optimum of the PL in optical localization.展开更多
To simplify the fabrication process and increase the versatility of neuromorphic systems,the reconfiguration concept has attracted much attention.Here,we developed a novel electrochemical VO_(2)(EC-VO_(2))device,which...To simplify the fabrication process and increase the versatility of neuromorphic systems,the reconfiguration concept has attracted much attention.Here,we developed a novel electrochemical VO_(2)(EC-VO_(2))device,which can be reconfigured as synapses or LIF neurons.The ionic dynamic doping contributed to the resistance changes of VO_(2),which enables the reversible modulation of device states.The analog resistance switching and tunable LIF functions were both measured based on the same device to demonstrate the capacity of reconfiguration.Based on the reconfigurable EC-VO_(2),the simulated spiking neural network model exhibited excellent performances by using low-precision weights and tunable output neurons,whose final accuracy reached 91.92%.展开更多
Automated optical inspection(AOI)is a significant process in printed circuit board assembly(PCBA)production lines which aims to detect tiny defects in PCBAs.Existing AOI equipment has several deficiencies including lo...Automated optical inspection(AOI)is a significant process in printed circuit board assembly(PCBA)production lines which aims to detect tiny defects in PCBAs.Existing AOI equipment has several deficiencies including low throughput,large computation cost,high latency,and poor flexibility,which limits the efficiency of online PCBA inspection.In this paper,a novel PCBA defect detection method based on a lightweight deep convolution neural network is proposed.In this method,the semantic segmentation model is combined with a rule-based defect recognition algorithm to build up a defect detection frame-work.To improve the performance of the model,extensive real PCBA images are collected from production lines as datasets.Some optimization methods have been applied in the model according to production demand and enable integration in lightweight computing devices.Experiment results show that the production line using our method realizes a throughput more than three times higher than traditional methods.Our method can be integrated into a lightweight inference system and pro-mote the flexibility of AOI.The proposed method builds up a general paradigm and excellent example for model design and optimization oriented towards industrial requirements.展开更多
The finding of the robust ferroelectricity in HfO_(2)-based thin films is fantastic from the view point of both the fundamentals and the applications.In this review article,the current research status of the future pr...The finding of the robust ferroelectricity in HfO_(2)-based thin films is fantastic from the view point of both the fundamentals and the applications.In this review article,the current research status of the future prospects for the ferroelectric HfO_(2)-based thin films and devices are presented from fundamentals to applications.The related issues are discussed,which include:1)The ferroelectric characteristics observed in HfO_(2)-based films and devices associated with the factors of dopant,strain,interface,thickness,defect,fabrication condition,and more;2)physical understanding on the observed ferroelectric behaviors by the density functional theory(DFT)-based theory calculations;3)the characterizations of microscopic and macroscopic features by transmission electron microscopes-based and electrical properties-based techniques;4)modeling and simulations,5)the performance optimizations,and 6)the applications of some ferroelectric-based devices such as ferroelectric random access memory,ferroelectric-based field effect transistors,and the ferroelectric tunnel junction for the novel information processing systems.展开更多
Importance:Brain-computer interface(BCI)decodes and converts brain signals into machine instructions to interoperate with the external world.However,limited by the implantation risks of invasive BCIs and the operation...Importance:Brain-computer interface(BCI)decodes and converts brain signals into machine instructions to interoperate with the external world.However,limited by the implantation risks of invasive BCIs and the operational complexity of conventional noninvasive BCIs,applications of BCIs are mainly used in laboratory or clinical environments,which are not conducive to the daily use of BCI devices.With the increasing demand for intelligent medical care,the development of wearable BCI systems is necessary.Highlights:Based on the scalp-electroencephalogram(EEG),forehead-EEG,and ear-EEG,the state-of-the-art wearable BCI devices for disease management and patient assistance are reviewed.This paper focuses on the EEG acquisition equipment of the novel wearable BCI devices and summarizes the development direction of wearable EEG-based BCI devices.Conclusions:BCI devices play an essential role in the medical field.This review briefly summarizes novel wearable EEG-based BCIs applied in the medical field and the latest progress in related technologies,emphasizing its potential to help doctors,patients,and caregivers better understand and utilize BCI devices.展开更多
Instead of 1 National Key Laboratory of Science and Technology on Micro/Nano Fabrication,School of Integrated Circuits,Peking University,Beijing 100871,China.
Cardiovascular diseases(CVDs)are one of the most serious diseases threatening human health in the world.Therefore,effective monitoring and treatment of CVDs are urgently needed.Compared with traditional rigid devices,...Cardiovascular diseases(CVDs)are one of the most serious diseases threatening human health in the world.Therefore,effective monitoring and treatment of CVDs are urgently needed.Compared with traditional rigid devices,nanomaterials based flexible devices open up new opportunities for further development beneficial from the unique properties of nanomaterials which contribute to excellent performance to better prevent and treat CVDs.This review summarizes recent advances of nanomaterials based flexible devices for the monitoring and treatment of CVDs.First,we review the outstanding characteristics of nanomaterials.Next,we introduce flexible devices based on nanomaterials for practical use in CVDs including in vivo,ex vivo,and in vitro methods.At last,we make a conclusion and discuss the further development needed for nanomaterials and monitoring and treatment devices to better care CVDs.展开更多
Surface lattice resonance(SLR)is a pretty effective mechanism to realize ultranarrow linewidths in the spectrum.Herein,we propose and demonstrate reflection-type SLRs in all-metal metasurfaces experimentally,compared ...Surface lattice resonance(SLR)is a pretty effective mechanism to realize ultranarrow linewidths in the spectrum.Herein,we propose and demonstrate reflection-type SLRs in all-metal metasurfaces experimentally,compared with the traditional transmission-type SLR,which can avoid the refractive index(RI)mismatch problem and are more suitable for high-efficiency RI sensing due to direct contact and strong light–matter interaction.The measured SLR linewidth is 13.5 nm influenced by the meta-atom size,which needs a compromise design to keep a balance between the narrow linewidth and noise immunity.Notably,the SLR sensitivity is determined by the lattice period along the polarization direction with regularity,which establishes an intuitive link between structures and optical responses and provides a theoretical guide for metasurface designs.Additionally,incident angle multiplexing will make the resonance wavelength red shift or blue shift in the case of orthogonal polarization.The rectangular array metasurface can realize dual SLRs with different sensing performances.Flexibly,the SLR can also be formed by the different meta-atoms and arrays.This research supports SLR multifarious applications involving not only RI sensing but also nonlinear optics,nano-lasers,etc.展开更多
Terahertz(THz)emission spectroscopy(TES)has emerged as a highly effective and versatile technique for investigating the photoelectric properties of diverse materials and nonlinear physical processes in the past few de...Terahertz(THz)emission spectroscopy(TES)has emerged as a highly effective and versatile technique for investigating the photoelectric properties of diverse materials and nonlinear physical processes in the past few decades.Concurrently,research on two-dimensional(2D)materials has experienced substantial growth due to their atomically thin structures,exceptional mechanical and optoelectronic properties,and the potential for applications in flexible electronics,sensing,and nanoelectronics.Specifically,these materials offer advantages such as tunable bandgap,high carrier mobility,wideband optical absorption,and relatively short carrier lifetime.By applying TES to investigate the 2D materials,their interfaces and heterostructures,rich information about the interplay among photons,charges,phonons and spins can be unfolded,which provides fundamental understanding for future applications.Thus it is timely to review the nonlinear processes underlying THz emission in 2D materials including optical rectification,photon-drag,high-order harmonic generation and spin-to-charge conversion,showcasing the rich diversity of the TES employed to unravel the complex nature of these materials.Typical applications based on THz emissions,such as THz lasers,ultrafast imaging and biosensors,are also discussed.Step further,we analyzed the unique advantages of spintronic terahertz emitters and the future technological advancements in the development of new THz generation mechanisms leading to advanced THz sources characterized by wide bandwidth,high power and integration,suitable for industrial and commercial applications.The continuous advancement and integration of TES with the study of 2D materials and heterostructures promise to revolutionize research in different areas,including basic materials physics,novel optoelectronic devices,and chips for post-Moore’s era.展开更多
Terahertz (THz) wave manipulation, especially the beam deflection, plays an essential role in various applications, such as next-generation communication, space exploration, and high-resolution imaging. Current THz op...Terahertz (THz) wave manipulation, especially the beam deflection, plays an essential role in various applications, such as next-generation communication, space exploration, and high-resolution imaging. Current THz optical components and devices are hampered by their large bulk sizes and passive responses, limiting the development of high-performance, miniaturized THz microsystems. Tunable metasurfaces offer a powerful dynamic optical platform for controlling the propagation of electromagnetic waves. In this article, we presented a mechanically tunable metasurface (MTM), which can achieve terahertz beam deflection and vary the intensity of the anomalous reflected terahertz wave by changing the air gap between the metallic resonator (MR) array with phase discontinuities and Au ground plane. The absence of lossy spacer materials substantially enhances deflection efficiency. The device was fabricated by a combination of the surface and bulk-micromachining processes. The THz beam steering capability was characterized using terahertz time domain spectroscopy. When the air gap is 50 μm, the maximum deflection coefficient reaches 0.60 at 0.61 THz with a deflection angle of ~44.5°, consistent with theoretical predictions. We further established an electrically tunable miniaturized THz device for dynamic beam steering by introducing a micro voice coil motor to control the air gap continuously. It is shown that our designed MTM demonstrates a high modulation depth of deflection coefficient (~ 62.5%) in the target steered angle at the operating frequency. Our results showcase the potential of the proposed MTM as a platform for high-efficiency THz beam manipulation.展开更多
Transport of ions and water is essential for diverse physiological activities and industrial applications.As the dimension approaches nano and even angstrom scale,ions and water exhibit anomalous behaviors that differ...Transport of ions and water is essential for diverse physiological activities and industrial applications.As the dimension approaches nano and even angstrom scale,ions and water exhibit anomalous behaviors that differ significantly from the bulk.One of the key reasons for these distinctive behaviors is the prominent influence of surface effects and related transport properties occurring at the interface under such(sub)nanoconfinement.Therefore,exploring nanofluidic transport at the interfaces could not only contribute to unraveling the intriguing ion and water transport behaviors but also facilitate the development of nanofluidic devices with tunable mass transport for practical applications.In this review,we focus on three crucial interfaces governing ion and water transport,namely liquid–gas interface,liquid–solid interface,and liquid–liquid interface,with emphasis on elucidating their intricate interfacial structures and critical roles for nanofluidic transport phenomena.Additionally,potential applications associated with liquid–gas,liquid–solid,and liquid–liquid interfaces are also discussed.Finally,we present a perspective on the pivotal roles of interfaces on nanofluidics,as well as challenges in this advancing field.展开更多
Optical measurement systems suffer from a fundamental tradeoff between the field of view(FOV),the resolution and the update rate.A compound eye has the advantages of a wide FOV,high update rate and high sensitivity to...Optical measurement systems suffer from a fundamental tradeoff between the field of view(FOV),the resolution and the update rate.A compound eye has the advantages of a wide FOV,high update rate and high sensitivity to motion,providing inspiration for breaking through the constraint and realizing high-performance optical systems.However,most existing studies on artificial compound eyes are limited by complex structure and low resolution,and they focus on imaging instead of precise measurement.Here,a high-performance lensless compound eye microsystem is developed to realize target motion perception through precise and fast orientation measurement.The microsystem splices multiple sub-FOVs formed by long-focal subeyes,images targets distributed in a panoramic range into a single multiplexing image sensor,and codes the subeye aperture array for distinguishing the targets from different sub-FOVs.A wide-field and high resolution are simultaneously realized in a simple and easy-to-manufacture microelectromechanical system(MEMS)aperture array.Moreover,based on the electronic rolling shutter technique of the image sensor,a hyperframe update rate is achieved by the precise measurement of multiple time-shifted spots of one target.The microsystem achieves an orientation measurement accuracy of 0.0023°(3σ)in the x direction and 0.0028°(3σ)in the y direction in a cone FOV of 120°with an update rate~20 times higher than the frame rate.This study provides a promising approach for achieving optical measurements with comprehensive high performance and may have great significance in various applications,such as vision-controlled directional navigation and high-dynamic target tracking,formation and obstacle avoidance of unmanned aerial vehicles.展开更多
The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporat...The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporated into the sensing of biomarkers,limiting the richness of sensing results.In this study,we report a time sequential sensing scheme for uric acid in sweat through a sequential design of Tesla valve channels.Graphene electrodes for detecting uric acid and directional Tesla valve flow channels were fabricated using laser engraving technology to realize time sequential sensing.The performance of the channels was verified through simulation.The time sequential detection of uric acid concentration in sweat can help researchers improve the establishment of human health management systems through flexible wearable devices.展开更多
Supercapacitors(SCs)have been successfully used in electric vehicles or military equipment systems for their high power density.However,the mechanical impacts from vehicle crashes and missile penetration probably caus...Supercapacitors(SCs)have been successfully used in electric vehicles or military equipment systems for their high power density.However,the mechanical impacts from vehicle crashes and missile penetration probably cause performance fluctuations or failure of SCs,which may threaten the safety of systems using SCs.In this paper,a generalized circuit model to analyze the transient process of SCs under mechanical loads is proposed.The circuit model simultaneously takes capacitance change,internal short-circuit and resistance change into account,an extra resistor-capacitor circuit(RCC)is added to simulate the nonlinear behavior during charging and discharging.Subsequently,the relationships between pressure and fundamental circuit parameters are determined by static methods.By taking the static test data into the circuit model,the transient response of different types of SCs under particular mechanical loading conditions is predicted.Finally,the influences of some crucial parameters on the voltage responses of SCs are revealed based on the simulations,which provide references for designing and optimizing mechanical load-resistant or self-sensing SCs in specific application scenarios.展开更多
Artificial van der Waals(vdWs)heterostructures offer unprecedented opportunities to explore and reveal novel synergistic electronic and optical phenomena,which are beneficial for the development of novel optoelectroni...Artificial van der Waals(vdWs)heterostructures offer unprecedented opportunities to explore and reveal novel synergistic electronic and optical phenomena,which are beneficial for the development of novel optoelectronic devices at atomic limits.However,due to the damage caused by the device fabrication process,their inherent properties such as carrier mobility are obscured,which hinders the improvement of device performance and the incorporation of vdWs materials into next-generation integrated circuits.Herein,combining pump-probe spectroscopic and scanning probe microscopic techniques,the intrinsic optoelectronic properties of PtSe_(2)/MoSe_(2)heterojunction were nondestructively and systematically investigated.The heterojunction exhibits a broad-spectrum optical response and maintains ultrafast carrier dynamics(interfacial charge transfer~0.8 ps and carrier lifetime~38.2 ps)simultaneously.The in-plane exciton diffusion coefficient of the heterojunction was extracted(19.4±7.6 cm^(2)∙s^(−1)),and its exciton mobility as high as 756.8 cm^(2)∙V−1∙s^(−1)was deduced,exceeding the value of its components.This enhancement was attributed to the formation of an n-type Schottky junction between PtSe_(2)and MoSe_(2),and its built-in electric field assisted the ultrafast transfer of photogenerated carriers from MoSe_(2)to PtSe_(2),enhancing the in-plane exciton diffusion of the heterojunction.Our results demonstrate that PtSe_(2)/MoSe_(2)is suitable for the development of broadspectrum and sensitive optoelectronic devices.Meanwhile,the results contribute to a fundamental understanding of the performance of various optoelectronic devices based on such PtSe_(2)two-dimensional(2D)heterostructures.展开更多
The combinatorial optimization problem(COP),which aims to find the optimal solution in discrete space,is fundamental in various fields.Unfortunately,many COPs are NP-complete,and require much more time to solve as the...The combinatorial optimization problem(COP),which aims to find the optimal solution in discrete space,is fundamental in various fields.Unfortunately,many COPs are NP-complete,and require much more time to solve as the problem scale increases.Troubled by this,researchers may prefer fast methods even if they are not exact,so approximation algorithms,heuristic algorithms,and machine learning have been proposed.Some works proposed chaotic simulated annealing(CSA)based on the Hopfield neural network and did a good job.However,CSA is not something that current general-purpose processors can handle easily,and there is no special hardware for it.To efficiently perform CSA,we propose a software and hardware co-design.In software,we quantize the weight and output using appropriate bit widths,and then modify the calculations that are not suitable for hardware implementation.In hardware,we design a specialized processing-in-memory hardware architecture named COPPER based on the memristor.COPPER is capable of efficiently running the modified quantized CSA algorithm and supporting the pipeline further acceleration.The results show that COPPER can perform CSA remarkably well in both speed and energy.展开更多
The generation and manipulation of spin-polarized current are critical for spintronic devices.In this work,we propose a mechanism to generate and switch spin-polarized current by an electric field in multiferroic tunn...The generation and manipulation of spin-polarized current are critical for spintronic devices.In this work,we propose a mechanism to generate and switch spin-polarized current by an electric field in multiferroic tunnel junctions(MFTJs),with symmetric interface terminations in an antiparallel magnetic state.In such devices,different spin tunneling barriers are realized by the magnetoelectric coupling effect,resulting in a spin-polarized current.By reversing the electric polarization of the ferroelectric layer,the spin polarization of current is efficiently switched for the exchange of spin tunneling barriers.By first-principles quantum transport calculations,we show that a highly spin-polarized current is obtained and manipulated by the electric field in hafnia-based MFTJs based on the proposed mechanism.We also demonstrate that four resistance states are realized in Co/HfO_(2)/Co junctions with asymmetric interface terminations.This work provides a promising approach for realizing the electrical control of spin current for spintronic applications.展开更多
Gas transport under confinement exhibits a plethora of physical and chemical phenomena that differ from those observed in bulk media,owing to the deviations of continuum description at the molecular level.In biologica...Gas transport under confinement exhibits a plethora of physical and chemical phenomena that differ from those observed in bulk media,owing to the deviations of continuum description at the molecular level.In biological systems,gas channels play indispen-sable roles in various physiological functions by regulating gas transport across cell membranes.Therefore,investigating gas trans-port under such confinement is crucial for comprehending cellular physiological activities.Moreover,leveraging these underlying mechanisms can enable the construction of bioinspired artificial nanofluidic devices with tailored gas transport properties akin to those found in biological channels.This review provides a comprehensive summary of confined gas transport mechanisms,focusing on the unique effects arising from nanoconfinement.Additionally,we categorize nanoconfinement spaces based on dimensionality to elucidate their control over gas transport beha-vior.Finally,we highlight the potential of bioinspired smart gas membranes that mimic precise modulation of transportation observed in organisms.To conclude,we present a concise outlook on the challenges and opportunities in this rapidly expanding field.展开更多
基金supported by National Key R&D Program of China(2020YFB2008704)the National Natural Science Foundation of China(62004114 and 62174098)+1 种基金Beijing Municipal Science and Technology Commission(Z221100005822011)The Tsinghua-Foshan Innovation Special Fund(2021THFS0215)。
文摘As Moore’s law deteriorates,the research and development of new materials system are crucial for transitioning into the post Moore era.Traditional semiconductor materials,such as silicon,have served as the cornerstone of modern technologies for over half a century.This has been due to extensive research and engineering on new techniques to continuously enrich silicon-based materials system and,subsequently,to develop better performed silicon-based devices.Meanwhile,in the emerging post Moore era,layered semiconductor materials,such as transition metal dichalcogenides(TMDs),have garnered considerable research interest due to their unique electronic and optoelectronic properties,which hold great promise for powering the new era of next generation electronics.As a result,techniques for engineering the properties of layered semiconductors have expanded the possibilities of layered semiconductor-based devices.However,there remain significant limitations in the synthesis and engineering of layered semiconductors,impeding the utilization of layered semiconductor-based devices for mass applications.As a practical alternative,heterogeneous integration between layered and traditional semiconductors provides valuable opportunities to combine the distinctive properties of layered semiconductors with well-developed traditional semiconductors materials system.Here,we provide an overview of the comparative coherence between layered and traditional semiconductors,starting with TMDs as the representation of layered semiconductors.We highlight the meaningful opportunities presented by the heterogeneous integration of layered semiconductors with traditional semiconductors,representing an optimal strategy poised to propel the emerging semiconductor research community and chip industry towards unprecedented advancements in the coming decades.
基金the support from the National Natural Science Foundation of China(51827806)the National Key Research and Development Program of China(2016YFB0501201)the Xplorer Prize funded by the Tencent Foundation。
文摘Subpixel localization techniques for estimating the positions of point-like images captured by pixelated image sensors have been widely used in diverse optical measurement fields.With unavoidable imaging noise,there is a precision limit(PL)when estimating the target positions on image sensors,which depends on the detected photon count,noise,point spread function(PSF)radius,and PSF’s intra-pixel position.Previous studies have clearly reported the effects of the first three parameters on the PL but have neglected the intra-pixel position information.Here,we develop a localization PL analysis framework for revealing the effect of the intra-pixel position of small PSFs.To accurately estimate the PL in practical applications,we provide effective PSF(e PSF)modeling approaches and apply the Cramér–Rao lower bound.Based on the characteristics of small PSFs,we first derive simplified equations for finding the best PL and the best intra-pixel region for an arbitrary small PSF;we then verify these equations on real PSFs.Next,we use the typical Gaussian PSF to perform a further analysis and find that the final optimum of the PL is achieved at the pixel boundaries when the Gaussian radius is as small as possible,indicating that the optimum is ultimately limited by light diffraction.Finally,we apply the maximum likelihood method.Its combination with e PSF modeling allows us to successfully reach the PL in experiments,making the above theoretical analysis effective.This work provides a new perspective on combining image sensor position control with PSF engineering to make full use of information theory,thereby paving the way for thoroughly understanding and achieving the final optimum of the PL in optical localization.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61925401,92064004,61927901,and 92164302)the 111 Project (Grant No.B18001)+1 种基金support from the Fok Ying-Tong Education Foundationthe Tencent Foundation through the XPLORER PRIZE。
文摘To simplify the fabrication process and increase the versatility of neuromorphic systems,the reconfiguration concept has attracted much attention.Here,we developed a novel electrochemical VO_(2)(EC-VO_(2))device,which can be reconfigured as synapses or LIF neurons.The ionic dynamic doping contributed to the resistance changes of VO_(2),which enables the reversible modulation of device states.The analog resistance switching and tunable LIF functions were both measured based on the same device to demonstrate the capacity of reconfiguration.Based on the reconfigurable EC-VO_(2),the simulated spiking neural network model exhibited excellent performances by using low-precision weights and tunable output neurons,whose final accuracy reached 91.92%.
基金supported in part by the IoT Intelligent Microsystem Center of Tsinghua University-China Mobile Joint Research Institute.
文摘Automated optical inspection(AOI)is a significant process in printed circuit board assembly(PCBA)production lines which aims to detect tiny defects in PCBAs.Existing AOI equipment has several deficiencies including low throughput,large computation cost,high latency,and poor flexibility,which limits the efficiency of online PCBA inspection.In this paper,a novel PCBA defect detection method based on a lightweight deep convolution neural network is proposed.In this method,the semantic segmentation model is combined with a rule-based defect recognition algorithm to build up a defect detection frame-work.To improve the performance of the model,extensive real PCBA images are collected from production lines as datasets.Some optimization methods have been applied in the model according to production demand and enable integration in lightweight computing devices.Experiment results show that the production line using our method realizes a throughput more than three times higher than traditional methods.Our method can be integrated into a lightweight inference system and pro-mote the flexibility of AOI.The proposed method builds up a general paradigm and excellent example for model design and optimization oriented towards industrial requirements.
基金supported by National Key Research and Development Program(grant 2019YFB2205100)National Science Foundation of China(grant 92064001)。
文摘The finding of the robust ferroelectricity in HfO_(2)-based thin films is fantastic from the view point of both the fundamentals and the applications.In this review article,the current research status of the future prospects for the ferroelectric HfO_(2)-based thin films and devices are presented from fundamentals to applications.The related issues are discussed,which include:1)The ferroelectric characteristics observed in HfO_(2)-based films and devices associated with the factors of dopant,strain,interface,thickness,defect,fabrication condition,and more;2)physical understanding on the observed ferroelectric behaviors by the density functional theory(DFT)-based theory calculations;3)the characterizations of microscopic and macroscopic features by transmission electron microscopes-based and electrical properties-based techniques;4)modeling and simulations,5)the performance optimizations,and 6)the applications of some ferroelectric-based devices such as ferroelectric random access memory,ferroelectric-based field effect transistors,and the ferroelectric tunnel junction for the novel information processing systems.
基金the National Key Research and Development Program of China(nos.2022YFF1202301 and 2022YFF1502100)the National Natural Science Foundation of China(no.62004007)the China Postdoctoral Science Foundation(no.2021M700258).
文摘Importance:Brain-computer interface(BCI)decodes and converts brain signals into machine instructions to interoperate with the external world.However,limited by the implantation risks of invasive BCIs and the operational complexity of conventional noninvasive BCIs,applications of BCIs are mainly used in laboratory or clinical environments,which are not conducive to the daily use of BCI devices.With the increasing demand for intelligent medical care,the development of wearable BCI systems is necessary.Highlights:Based on the scalp-electroencephalogram(EEG),forehead-EEG,and ear-EEG,the state-of-the-art wearable BCI devices for disease management and patient assistance are reviewed.This paper focuses on the EEG acquisition equipment of the novel wearable BCI devices and summarizes the development direction of wearable EEG-based BCI devices.Conclusions:BCI devices play an essential role in the medical field.This review briefly summarizes novel wearable EEG-based BCIs applied in the medical field and the latest progress in related technologies,emphasizing its potential to help doctors,patients,and caregivers better understand and utilize BCI devices.
基金the National Natural Science Foundation of China(No.62104009)the National Key Research and Development Program of China(No.2018YFA0108100).
文摘Instead of 1 National Key Laboratory of Science and Technology on Micro/Nano Fabrication,School of Integrated Circuits,Peking University,Beijing 100871,China.
基金supported by the National Key R&D Program of China(No.2018YFA0108100)the National Natural Science Foundation of China(No.62104009).
文摘Cardiovascular diseases(CVDs)are one of the most serious diseases threatening human health in the world.Therefore,effective monitoring and treatment of CVDs are urgently needed.Compared with traditional rigid devices,nanomaterials based flexible devices open up new opportunities for further development beneficial from the unique properties of nanomaterials which contribute to excellent performance to better prevent and treat CVDs.This review summarizes recent advances of nanomaterials based flexible devices for the monitoring and treatment of CVDs.First,we review the outstanding characteristics of nanomaterials.Next,we introduce flexible devices based on nanomaterials for practical use in CVDs including in vivo,ex vivo,and in vitro methods.At last,we make a conclusion and discuss the further development needed for nanomaterials and monitoring and treatment devices to better care CVDs.
基金National Natural Science Foundation of China(61974004,61931018)National Key Research and Development Program of China(2021YFB3200100)。
文摘Surface lattice resonance(SLR)is a pretty effective mechanism to realize ultranarrow linewidths in the spectrum.Herein,we propose and demonstrate reflection-type SLRs in all-metal metasurfaces experimentally,compared with the traditional transmission-type SLR,which can avoid the refractive index(RI)mismatch problem and are more suitable for high-efficiency RI sensing due to direct contact and strong light–matter interaction.The measured SLR linewidth is 13.5 nm influenced by the meta-atom size,which needs a compromise design to keep a balance between the narrow linewidth and noise immunity.Notably,the SLR sensitivity is determined by the lattice period along the polarization direction with regularity,which establishes an intuitive link between structures and optical responses and provides a theoretical guide for metasurface designs.Additionally,incident angle multiplexing will make the resonance wavelength red shift or blue shift in the case of orthogonal polarization.The rectangular array metasurface can realize dual SLRs with different sensing performances.Flexibly,the SLR can also be formed by the different meta-atoms and arrays.This research supports SLR multifarious applications involving not only RI sensing but also nonlinear optics,nano-lasers,etc.
基金the National Key Research and Development Program of China(2021YFA1200800)the National Natural Science Foundation of China(62004114 and 62174098)Tsinghua University Initiative Scientific Research Center,Beijing Municipal Science and Technology Commission(Z221100005822011)and Beijing Advanced Innovation Center.
文摘Terahertz(THz)emission spectroscopy(TES)has emerged as a highly effective and versatile technique for investigating the photoelectric properties of diverse materials and nonlinear physical processes in the past few decades.Concurrently,research on two-dimensional(2D)materials has experienced substantial growth due to their atomically thin structures,exceptional mechanical and optoelectronic properties,and the potential for applications in flexible electronics,sensing,and nanoelectronics.Specifically,these materials offer advantages such as tunable bandgap,high carrier mobility,wideband optical absorption,and relatively short carrier lifetime.By applying TES to investigate the 2D materials,their interfaces and heterostructures,rich information about the interplay among photons,charges,phonons and spins can be unfolded,which provides fundamental understanding for future applications.Thus it is timely to review the nonlinear processes underlying THz emission in 2D materials including optical rectification,photon-drag,high-order harmonic generation and spin-to-charge conversion,showcasing the rich diversity of the TES employed to unravel the complex nature of these materials.Typical applications based on THz emissions,such as THz lasers,ultrafast imaging and biosensors,are also discussed.Step further,we analyzed the unique advantages of spintronic terahertz emitters and the future technological advancements in the development of new THz generation mechanisms leading to advanced THz sources characterized by wide bandwidth,high power and integration,suitable for industrial and commercial applications.The continuous advancement and integration of TES with the study of 2D materials and heterostructures promise to revolutionize research in different areas,including basic materials physics,novel optoelectronic devices,and chips for post-Moore’s era.
基金the National Key R&D Program of China(Grant No.2021YFB2011800)the National Nature Science Foundation of China(Grant No.U21A6003)+1 种基金the United Science Foundation of Ministry of Education of China(Grant No.8091B032115)the Beijing Natural Science Foundation(Grant No.422068).X.Z.acknowledges the startup funding from Tsinghua University.
文摘Terahertz (THz) wave manipulation, especially the beam deflection, plays an essential role in various applications, such as next-generation communication, space exploration, and high-resolution imaging. Current THz optical components and devices are hampered by their large bulk sizes and passive responses, limiting the development of high-performance, miniaturized THz microsystems. Tunable metasurfaces offer a powerful dynamic optical platform for controlling the propagation of electromagnetic waves. In this article, we presented a mechanically tunable metasurface (MTM), which can achieve terahertz beam deflection and vary the intensity of the anomalous reflected terahertz wave by changing the air gap between the metallic resonator (MR) array with phase discontinuities and Au ground plane. The absence of lossy spacer materials substantially enhances deflection efficiency. The device was fabricated by a combination of the surface and bulk-micromachining processes. The THz beam steering capability was characterized using terahertz time domain spectroscopy. When the air gap is 50 μm, the maximum deflection coefficient reaches 0.60 at 0.61 THz with a deflection angle of ~44.5°, consistent with theoretical predictions. We further established an electrically tunable miniaturized THz device for dynamic beam steering by introducing a micro voice coil motor to control the air gap continuously. It is shown that our designed MTM demonstrates a high modulation depth of deflection coefficient (~ 62.5%) in the target steered angle at the operating frequency. Our results showcase the potential of the proposed MTM as a platform for high-efficiency THz beam manipulation.
基金the support from the grants of the National Natural Science Foundation of China(NSFC No.62274004,No.62004004,and T2188101).
文摘Transport of ions and water is essential for diverse physiological activities and industrial applications.As the dimension approaches nano and even angstrom scale,ions and water exhibit anomalous behaviors that differ significantly from the bulk.One of the key reasons for these distinctive behaviors is the prominent influence of surface effects and related transport properties occurring at the interface under such(sub)nanoconfinement.Therefore,exploring nanofluidic transport at the interfaces could not only contribute to unraveling the intriguing ion and water transport behaviors but also facilitate the development of nanofluidic devices with tunable mass transport for practical applications.In this review,we focus on three crucial interfaces governing ion and water transport,namely liquid–gas interface,liquid–solid interface,and liquid–liquid interface,with emphasis on elucidating their intricate interfacial structures and critical roles for nanofluidic transport phenomena.Additionally,potential applications associated with liquid–gas,liquid–solid,and liquid–liquid interfaces are also discussed.Finally,we present a perspective on the pivotal roles of interfaces on nanofluidics,as well as challenges in this advancing field.
基金the National Natural Science Foundation of China(51827806)the National Key Research and Development Program of China(2016YFB0501201).
文摘Optical measurement systems suffer from a fundamental tradeoff between the field of view(FOV),the resolution and the update rate.A compound eye has the advantages of a wide FOV,high update rate and high sensitivity to motion,providing inspiration for breaking through the constraint and realizing high-performance optical systems.However,most existing studies on artificial compound eyes are limited by complex structure and low resolution,and they focus on imaging instead of precise measurement.Here,a high-performance lensless compound eye microsystem is developed to realize target motion perception through precise and fast orientation measurement.The microsystem splices multiple sub-FOVs formed by long-focal subeyes,images targets distributed in a panoramic range into a single multiplexing image sensor,and codes the subeye aperture array for distinguishing the targets from different sub-FOVs.A wide-field and high resolution are simultaneously realized in a simple and easy-to-manufacture microelectromechanical system(MEMS)aperture array.Moreover,based on the electronic rolling shutter technique of the image sensor,a hyperframe update rate is achieved by the precise measurement of multiple time-shifted spots of one target.The microsystem achieves an orientation measurement accuracy of 0.0023°(3σ)in the x direction and 0.0028°(3σ)in the y direction in a cone FOV of 120°with an update rate~20 times higher than the frame rate.This study provides a promising approach for achieving optical measurements with comprehensive high performance and may have great significance in various applications,such as vision-controlled directional navigation and high-dynamic target tracking,formation and obstacle avoidance of unmanned aerial vehicles.
基金supported by the National Key R&D Program of China(No.2018YFA0108100)the National Natural Science Foundation of China(No.62104009)Experiments on human sweat were conducted in accordance with the approved protocol from the institutional review board at Peking University Third Hospital,Beijing,China(No.M2021610).
文摘The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporated into the sensing of biomarkers,limiting the richness of sensing results.In this study,we report a time sequential sensing scheme for uric acid in sweat through a sequential design of Tesla valve channels.Graphene electrodes for detecting uric acid and directional Tesla valve flow channels were fabricated using laser engraving technology to realize time sequential sensing.The performance of the channels was verified through simulation.The time sequential detection of uric acid concentration in sweat can help researchers improve the establishment of human health management systems through flexible wearable devices.
基金the National Natural Science Foundation of China(No.52007084)the Natural Science Foundation of Jiangsu Province under Grant(No.BK20190470).
文摘Supercapacitors(SCs)have been successfully used in electric vehicles or military equipment systems for their high power density.However,the mechanical impacts from vehicle crashes and missile penetration probably cause performance fluctuations or failure of SCs,which may threaten the safety of systems using SCs.In this paper,a generalized circuit model to analyze the transient process of SCs under mechanical loads is proposed.The circuit model simultaneously takes capacitance change,internal short-circuit and resistance change into account,an extra resistor-capacitor circuit(RCC)is added to simulate the nonlinear behavior during charging and discharging.Subsequently,the relationships between pressure and fundamental circuit parameters are determined by static methods.By taking the static test data into the circuit model,the transient response of different types of SCs under particular mechanical loading conditions is predicted.Finally,the influences of some crucial parameters on the voltage responses of SCs are revealed based on the simulations,which provide references for designing and optimizing mechanical load-resistant or self-sensing SCs in specific application scenarios.
基金supported by the National Natural Science Foundation of China(Nos.11974088,61975007,52172060,61925401,92064004,61927901,and 92164302)the Beijing Natural Science Foundation(Nos.Z190006 and 4222073)+1 种基金the National Key R&D Program of China(No.2018YFA0208402),the 111 Project(No.B18001)the Fok Ying-Tong Education Foundation,and the Tencent Foundation through the XPLORER PRIZE。
文摘Artificial van der Waals(vdWs)heterostructures offer unprecedented opportunities to explore and reveal novel synergistic electronic and optical phenomena,which are beneficial for the development of novel optoelectronic devices at atomic limits.However,due to the damage caused by the device fabrication process,their inherent properties such as carrier mobility are obscured,which hinders the improvement of device performance and the incorporation of vdWs materials into next-generation integrated circuits.Herein,combining pump-probe spectroscopic and scanning probe microscopic techniques,the intrinsic optoelectronic properties of PtSe_(2)/MoSe_(2)heterojunction were nondestructively and systematically investigated.The heterojunction exhibits a broad-spectrum optical response and maintains ultrafast carrier dynamics(interfacial charge transfer~0.8 ps and carrier lifetime~38.2 ps)simultaneously.The in-plane exciton diffusion coefficient of the heterojunction was extracted(19.4±7.6 cm^(2)∙s^(−1)),and its exciton mobility as high as 756.8 cm^(2)∙V−1∙s^(−1)was deduced,exceeding the value of its components.This enhancement was attributed to the formation of an n-type Schottky junction between PtSe_(2)and MoSe_(2),and its built-in electric field assisted the ultrafast transfer of photogenerated carriers from MoSe_(2)to PtSe_(2),enhancing the in-plane exciton diffusion of the heterojunction.Our results demonstrate that PtSe_(2)/MoSe_(2)is suitable for the development of broadspectrum and sensitive optoelectronic devices.Meanwhile,the results contribute to a fundamental understanding of the performance of various optoelectronic devices based on such PtSe_(2)two-dimensional(2D)heterostructures.
基金Project supported by the National Natural Science Foundation of China(Nos.61832020,62032001,92064006,and 62274036)the Beijing Academy of Artificial Intelligence(BAAI)of Chinathe 111 Project of China(No.B18001)。
文摘The combinatorial optimization problem(COP),which aims to find the optimal solution in discrete space,is fundamental in various fields.Unfortunately,many COPs are NP-complete,and require much more time to solve as the problem scale increases.Troubled by this,researchers may prefer fast methods even if they are not exact,so approximation algorithms,heuristic algorithms,and machine learning have been proposed.Some works proposed chaotic simulated annealing(CSA)based on the Hopfield neural network and did a good job.However,CSA is not something that current general-purpose processors can handle easily,and there is no special hardware for it.To efficiently perform CSA,we propose a software and hardware co-design.In software,we quantize the weight and output using appropriate bit widths,and then modify the calculations that are not suitable for hardware implementation.In hardware,we design a specialized processing-in-memory hardware architecture named COPPER based on the memristor.COPPER is capable of efficiently running the modified quantized CSA algorithm and supporting the pipeline further acceleration.The results show that COPPER can perform CSA remarkably well in both speed and energy.
基金This work was supported by the National Key Research and Development Program of China under Grant 2019YFB2205100the National Natural Science Foundation of China under Grant 61974003 and the 111 Project(B18001).
文摘The generation and manipulation of spin-polarized current are critical for spintronic devices.In this work,we propose a mechanism to generate and switch spin-polarized current by an electric field in multiferroic tunnel junctions(MFTJs),with symmetric interface terminations in an antiparallel magnetic state.In such devices,different spin tunneling barriers are realized by the magnetoelectric coupling effect,resulting in a spin-polarized current.By reversing the electric polarization of the ferroelectric layer,the spin polarization of current is efficiently switched for the exchange of spin tunneling barriers.By first-principles quantum transport calculations,we show that a highly spin-polarized current is obtained and manipulated by the electric field in hafnia-based MFTJs based on the proposed mechanism.We also demonstrate that four resistance states are realized in Co/HfO_(2)/Co junctions with asymmetric interface terminations.This work provides a promising approach for realizing the electrical control of spin current for spintronic applications.
基金the support from the grants of the National Natural Science Foundation of China(NSFC)[Grant No.62274004 and T2188101].
文摘Gas transport under confinement exhibits a plethora of physical and chemical phenomena that differ from those observed in bulk media,owing to the deviations of continuum description at the molecular level.In biological systems,gas channels play indispen-sable roles in various physiological functions by regulating gas transport across cell membranes.Therefore,investigating gas trans-port under such confinement is crucial for comprehending cellular physiological activities.Moreover,leveraging these underlying mechanisms can enable the construction of bioinspired artificial nanofluidic devices with tailored gas transport properties akin to those found in biological channels.This review provides a comprehensive summary of confined gas transport mechanisms,focusing on the unique effects arising from nanoconfinement.Additionally,we categorize nanoconfinement spaces based on dimensionality to elucidate their control over gas transport beha-vior.Finally,we highlight the potential of bioinspired smart gas membranes that mimic precise modulation of transportation observed in organisms.To conclude,we present a concise outlook on the challenges and opportunities in this rapidly expanding field.
